Influence of Iodine Vapour Pressure on Formation of XeI^＊ in Xe/I2 Mixture

The influence of the iodine vapour pressure on the mechanisms of XeI^＊ formation is investigated in Xe/I2 mixture by dielectric barrier discharge. The iodine vapour pressure is measured as a function of the ultraviolet （UV） intensity of XeI^＊ emission at 253 nm, and found that the UV intensity reaches a maximum at 0.9 Torr of iodine at a xenon pressure of 300 Torr, then decreases slowly with the iodine pressure larger than 0.9 Torr. The discharge mode transforms from a hybrid discharge at a xenon pressure of 760 Torr with 1.0 Torr of iodine to a diffuse mode at 10 Torr of iodine. These results are quite different from those of other rare-gas halogen excimers and indicate a different mechanism of XeI^＊ formation from those of other rare-gas halogen excimers.